The invention relates to a purifying device for liquid, that has filtering means in order to separate impurities in the liquid to be treated by mechanical filtration and purifying means, such as an activated carbon element or like, in order to eliminate impurities in the liquid to be treated by absorbtion or correspondingly, which means are arranged essentially built-in therein.
The type of purifying devices for liquid as described above, such as water purifiers are being used nowadays, in which a ceramic filter has been used as the filtering means and furthermore activated carbon material inside the ceramic filter acting as the purifying means.
The operating of the type of structure described above is inadequate considering particularly bacteria protection, because bacteria existing in the liquid to be treated, such as e.g. in dirty water, may not be eliminated hundred-procent by a ceramic filter with reasonable costs, but instead a part of the bacteria may penetrate the whole structure. This is why water, that is filtered by the type of structure in question, may not be exploited under all circumstances. Furthermore one disadvantage of ceramic material is such, that the ceramic filtering material absorbs substances existing in the water to be treated, such as humus or like, which is why it first of all gets dyed thoroughly and on the other hand naturally lets a large quantity of fine-grained humus through the same. When using this type of solution, one may not under all circumstances have full certainty, whether the water that has been treated is totally safe for drinking, that is why it is safest to avoid use of the type of purifying device described above under particularly disadvantageous circumstances.
On the other hand in the Finnish Patent, number 98810 there has been presented a type of a water purification device, that differs from what has been described above and that has a so called Membrane-structured filtering part. The solution in question is meant to operate on so called syphon principle, thanks to which the structure of the same is very simple. The water purification device in question is very safe and easy to use in practice, because the quality of the water flowing to the collecting point, taking place thanks to the syphon phenomenon self-powered and continuously, is always homogeneous regardless of the operating time of the device. This is first of all due to the fact, that a water purification device equipped with a thin PTM- or TeM filtering film does not at any stage let through material parts exceeding a certain particle size, in which case, when the filtering film gets dirty, only the penetration speed of the filter decreases and may even totally be interrupted, in case the filtering film is not cleaned every now and then.
The type of device described above is very easy to use in most heterogeneous connections, e.g. for filtering of lake water on terrain or under other circumstances as well, in which actual tap water may not be exploited. A disadvantage of the device in question is mainly the slowness of its filtering speed and on the other hand also the fact, that e.g. in ordinary household use the device requires use of separate vessels, so that the syphon phenomenon may be carried out.
Furthermore in the Finnish Patent Application, number 965249, xe2x80x9cMethod and apparatus for treatment of liquidxe2x80x9d there has been presented a more developed solution with respect to the above, in which the filtering film is being cleaned by means of cleaning means essentially self-powered, whereby first of all the primary side of the filtering film is being flushed by means of a by-pass flow of the liquid to be treated taking place advantageously tangentially. The solution in question has furthermore such a characteristic, that for cleaning of the filtering film a so called inverse flow is being exploited, that is carried out by leading liquid, that has been treated, such as e.g. filtered water, from an intermediate storing space, that has been connected to the secondary side of the filters, as a flow-through, that takes place through the filtering means in opposite direction with respect to the filtration flow.
Thanks to the solution above, that may be exploited first of all by connecting the same directly to a pressurized water system, the filtering film may be cleaned in an extremely simple, quick and reliable way. In addition to that one crucial advantage of the arrangement above is also the fact, that there is not any more need for manual cleaning measures of the filtering film, that is why direct mechanical rubbing of the filtering film may not occur.
The type of developed Membrane-structures described above are not however completely developed in view of all parts of the same. Thus when it is among other things desired to absorb substances of water simultaneously when the same is being filtered, in this connection e.g. totally separate activated carbon filters must have been used, that have been coupled so to say in series with the Membrane-film. This has naturally such a consequence, that a water purifying device equipped e.g. with an activated carbon filter being carried out traditionally as described above, brings out a disproportionately complicated and large entirety.
It is the aim of the purifying device for liquid according to this invention to achieve a decisive improvement over the prior art in order to address the problems presented above. In order to carry out this aim, the mechanical filtering means include a thin filtering film 1a made of plastic based material, such as PTM (Particle Track Membrane), TeM (Track-edge Membrane) or the like, the porosity of which is 5-15%, the thickness of which is preferably 10-25 xcexcm and having a pore size of 0.5 xcexcm at its height.
The purifying device for liquid according to the invention offers a very simple and at the same time however also an extremely safe entirety, by means of which it is possible simultaneously with the mechanical filtration to carry out also a safe treatment of the liquid to be treated, such as of drinking water, in order to e.g. absorb the harmful substances existing therein by activated carbon. One significant advantage of the invention is also the fact, that an efficient pre-filtration before e.g. an activated carbon material increases the operating time of the activated carbon material manyfold. In addition to that, a thin film material enables as large quantity of activated carbon as possible, in which case also the operating conditions for the same are optimal. So, the purifying device for liquid according to the invention is structurally very simple, because the structure inside the Membrane-film, that is formed advantageously of a fixed activated carbon cylinder, while doing its own primary functioning also supports the Membrane-film, so that there is no need anymore for use of a separate support structure for the Membrane-film in this connection. On the other hand the existing activated carbon solutions, that are internal e.g. within ceramic material are based on grain-like carbon, which is not able to operate as reliably as a totally homogeneous fixed cylinder, through which water is xe2x80x9cforcedxe2x80x9d. In this connection thanks to an elongated pipe structure being exploited with the purifying device for liquid it is possible to take advantage of those other parts of already existing water purifying device structures, into which a water filtering cartridge, that is carried out according to the invention, may be installed on quickrelease principle, such as by a screw joint, clamp joint, bayonet joint and/or correspondingly. In this connection the Membrane-film is arranged advantageously furthermore as a strenghtened structure by using a suitable strenghtening layer, that is connected in connection with the same e.g. by lamination.
As a summary of the advantages of the purifying device for liquid according to the invention, technical reliability and safety of its use may be mentioned, because the uniform plane structure of the filtering film being exploited therewith as well as those essentially cylindrical holes of the film enable first of all cleaning of the filtering film without the risk of the film getting damaged. In addition to that the cylindrical holes make sure of the reliable operating of the filtering film particularly in view of prevention of e.g. bacteria penetration, because the size of pores is at each point of the filtering film always within allowed limits at its height.
The non-independent claims related to the purifying device for liquid set forth preferred embodiments of the purifying device for liquid according to the invention.